Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=true, openWorldHint=true, idempotentHint=true, and destructiveHint=false, covering the safety profile. The description adds behavioral detail by specifying the exact fields returned and the optional filtering behavior, going beyond the annotations. It doesn't mention pagination or rate limits, but with annotations the read-only, side-effect-free nature is clear.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is three sentences, front-loads the core function, and each sentence earns its place: enumerating outputs, explaining the optional filter, and giving a usage recommendation. No wasted words or boilerplate.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

The tool is simple with one optional parameter, an output schema exists, and annotations already cover safety. The description addresses what data is returned, how to filter, and when to use it, making it fully adequate for an agent to select and invoke correctly. The output schema makes explicit return-value documentation unnecessary.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The input schema has 100% coverage for the only parameter, region, including all enum values and a full description. The description simply restates the sub-region values without adding any new semantics or usage nuance beyond the schema. Since schema coverage is full, baseline of 3 is appropriate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a specific verb ('List'), a specific resource ('all 54 African countries'), and enumerates the returned data fields (ISO codes, capitals, regional classifications, currencies, languages, area, timezone, border countries). It also names the optional sub-region filter, clearly distinguishing it from sibling tools like africa.data.indicator or africa.countries.signals.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description explicitly gives a usage context: 'Use as a discovery step to get country codes for other Africa API tools.' It also clarifies the optional region parameter and its accepted values. However, it does not name alternative tools or explicit conditions when not to use it, so it provides clear context but no exclusions.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.